Current responsive latching apparatus for disconnecting and isolating an electrical device

Abstract

A current responsive latching apparatus may be employed in a dropout fuseholder or other electrical component for retaining the component in a current-carrying position and disconnecting and isolating the electrical component upon the occurrence of an overcurrent of a predetermined magnitude. The apparatus includes a current path through the component, including a current-carrying stud or conductor, a portion of which extends outside the component for releasably engaging a support member. A latching apparatus, which may include an actuating member of memory allow or a bimetallic material, engages the conductor to retain the support member in a supporting position beneath the electrical component. The apparatus may further include a heater element in the current path to ensure that the actuation member is heated to the temperature necessary to cause it to change shape and release the conductor upon the presence of an overcurrent.

What is claimed is: 
     
       1. An electrical component comprising: a body;   a current path through said body;   a support member disposed adjacent to said body;   a conducting pin member extending from said body and releasably attached to said supporting member, said pin member forming a portion of said current path;   means for causing said pin member to release said support member when a current of a predetermined magnitude is conducted through said body.   
     
     
       2. The electrical component of claim 1 wherein said causing means comprises an actuating member engaging said pin. 
     
     
       3. The electrical component of claim 2 wherein said actuating member changes shape when it is heated to a predetermined temperature. 
     
     
       4. The electrical component of claim 3 wherein said actuating member comprises at least one latching extension, said extension engaging said actuating member pin when said is below said predetermined temperature and releasing said pin when said actuating member reaches said predetermined temperature. 
     
     
       5. The electrical component of claim 4 wherein said actuating member is made of a memory alloy. 
     
     
       6. The electrical component of claim 4 wherein said actuating member is made of a bimetallic material. 
     
     
       7. The electrical component of claim 4 wherein said actuating member comprises a clamping ring having a pair of arms disposed about said pin. 
     
     
       8. The electrical component of claim 4 wherein said pin includes at least one recess for engagement with said latching extensions of said actuating member. 
     
     
       9. The electrical component of claim 3 further comprising a heater element in said current path for causing said actuating member to reach said predetermined temperature when a current of a predetermined magnitude is conducted through said body. 
     
     
       10. The electrical component of claim 3 wherein said actuating member is disposed inside said body. 
     
     
       11. The electrical component of claim 3 wherein said actuating member is disposed outside said body. 
     
     
       12. A dropout fuseholder comprising: an insulative body;   first and second terminal assemblies on said body;   first and second current paths between said terminals, said paths electrically and parallel; wherein said first current path includes a fusible element; and   wherein said second current path comprises: a conducting pin having a portion extending out of said insulative body; and   a heat-responsive latching member releasably engaging said pin member.       
     
     
       13. The fuseholder of claim 12 wherein said second current path further comprises a resistive element for heating said latching member when current is conducted through said second current path. 
     
     
       14. The dropout fuseholder of claim 13 wherein said resistive element is formed of silicon carbide. 
     
     
       15. The dropout fuseholder of claim 13 wherein said latching member in said resistive element are disposed within said insulative body. 
     
     
       16. The dropout fuseholder of claim 13 wherein said latching member and said resistive element are disposed outside said insulative body. 
     
     
       17. The dropout fuseholder of claim 16 wherein said pin includes a retaining head attached to said portion of said pin that extends outside said insulative body, such free end of said latch member disposed between said conductive cap assembly and said retaining head of said pin. 
     
     
       18. The dropout fuseholder of claim 12 wherein said latching member is formed from a memory alloy and wherein said latching member releases said pin when said latching member is heated to a predetermined temperature. 
     
     
       19. The dropout fuseholder of claim 12 wherein said latching member is formed from a bimetallic material and wherein said latching member releases said pin when said latching member is heated to a predetermined temperature. 
     
     
       20. The dropout fuseholder of claim 12 wherein said latching member comprises a clamping ring having a first retaining and a second retaining arm disposed about said pin, said retaining arms releasing said pin when said clamping ring is heated to a predetermined temperature. 
     
     
       21. The dropout fuseholder of claim 12 wherein said second terminal assembly comprises a conductive end cap and a hinge assembly attached to said end cap; and wherein said hinge includes a latch member having a free end rotatable between a nonsupporting and a supporting position beneath said end cap, said free end of said latch member having an aperture therethrough; and   wherein said pin is disposed through said aperture of said latch member.